21 hp briggs vanguard question

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Thread: 21 hp briggs vanguard question

  1. #1
    Join Date
    Feb 2013
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    shenendoah valley,va.
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    21 hp briggs vanguard question

    hey friends ...i had to pull my motor out a few days ago , the starter had died . replaced it with a new starter ( briggs ) new solenoid . i changed the oil and filter and new spark plugs . got it back in , hooked up the wiring , etc. hit the key and it fired right up . it purred like a kitten .drove it around , turned it off and on several times and it worked great . after sitting maybe 2 days , i went out this afternoon , hit the key . the starter engaged but could'nt make the engine turn over . i reached in and pulled on the rope starter and it was really hard to pull on . i pulled harder and the engine '' freed up '' . i hit the key and it fired right up . drove around , turned it off and on numerous times with no problems . it's almost like after the engine sits awhile , it gets tight . any ideas , sticky valves ? valve adjustment ? i did'nt check to see if maybe the drive clutch was still grabbing the belt . any idears ? thanks always , johnboy va.

  2. #2
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    Nov 2020
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    Southwestern Ont Can about 5 miles from Lake Huron just north of the town of Goderich.
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    Check the oil for gas. Sounds like maybe the carb over flowed and hydrolocked a cylinder. Place to start anyway.

  3. #3
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    thanks laird ... and if thats the case , whats the cause ? the engines not that old . that sure sounds like what happens . i went out 3 hrs. later and it fired right up / any adjustments i need to do ? it sure runs excellent and strong . i appreciate your help . maybe some linkage on the carb needs looking at unless it's a internal engine thing . i'll see it it fires up in the morning after sitting overnite . appreciate it , johnboy

  4. #4
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    fired right up this morning ...if carb is overflowing , is that a float bowl issue or needle setting ? jb

  5. #5
    Join Date
    Nov 2021
    Location
    Western Ky
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    Easy way to check is next time it does it remove the spark plugs and see if it blows out gas. If it does there's yer problem. Should it be hydro lock then the problem will be the needle valve in the carb leaking. If it is running good for you a simple fix would be to put a shutoff valve in the gas line to turn off when it is not being used.

    Of course if does not do it again it could be it just had a piece of trash in the line that it held the valve open and it cleared itself when you ran the engine the next time.

  6. #6
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    jww .. i was looking at u tube videos about hydrolocking and it sounds like in most cases the carb needle and maybe the seat are worn , so gas leaks thru intake , etc to top of cylinders . i have a shutoff ..so i can turn that off at nite . does it hurt the motor to run it . ? maybe try replacing carb needle ? will it still leak gas even if motor is not running ? thanks , jboy

  7. #7
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    Nov 2020
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    Southwestern Ont Can about 5 miles from Lake Huron just north of the town of Goderich.
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    I am not familiar with the machine you have so I have no idea where your fuel tank is located. If any part of the fuel level is above the carb, then you could get a gravity feed past the needle and seat if they are leaking until the fuel level gets level with the carb. If the fuel has to be pumped up to the carb like an Argo, then I don't know how the carb would overflow into the cylinder. That being said, the pump may pump more than the engine needs and when you shut it down, the gas COULD puddle on top of a cylinder. On a lot of the Briggs 12,13,15 hp etc single cylinder lawnmower engines on the less expensive riders the tank is mounted high to gravity feed the carb and it is quite common for them to leak and fill the crankcase/hydolock the engine. If you shut the fuel flow off when you are not running it then you should be ok. Once it is running you will probably use the fuel going to the bowl. I personally check and double check the oil regularly for height on the dipstick and smell. Gas in the crankcase will take the bottom end out pretty quick if run for very long. If the oil doesn't smell of gas and when you pull a plug as was mentioned and no gas shoots out ,I would guess at MAYBE, an overheating issue locking up the engine. These are all just guess's but hopefully you get it sorted out. Briggs engines are generally fairly reliable......a statement others will disagree with but I have found them pretty good. Sorry but I tend to get long winded.

  8. #8
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    laird ..on my max 2 the gas tank is pretty much level or even a little lower than the carb. i will shut off fuel valve at the end of the day ..and keep an eye on oil level and gas smell . will check with the local small engine mechanic i know and see what he thinks about the carb needle and seat , if that may be a fix . they are'nt very expensive parts and don't look hard to replace . so nice how we can get such good feedback on this site on just about any question that's asked . thanks again , will post later final conclusion . jboy

  9. #9
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    I would not go tearing things apart until the problem has been isolated, you could end up messing other things up that are not now broke. Keep an eye on it and a check on the oil level, if the oil level increases then you can figure it is gas going past the rings from a leaking needle & seat. If it does not increase in level but only smells of gas then that would be more likely an indication the engine is running rich which you could also tell by the smell of the exhaust.

  10. #10
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    JWW is right on the money. A too rich carb can load up the cylinders and the unburnt gas will seep past the rings. This can happen more so if the machine idles for periods of time. If for some reason you can't smell the exhaust, run your finger around the inside of the exhaust pipe. If it comes out black and sooty it is a pretty good indication it could be running too rich. You'll get it figured out.

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